[unreadable] [unreadable] The long term objective of this proposal is to understand how environmental temperature fluctuations synchronize the Drosophila circadian clock. While many of the components of invertebrate and mammalian molecular circadian clocks have been identified, considerably less is known about how information from the environment synchronizes the internal molecular pacemaker. In this project, the effect of temperature fluctuations on Drosophila circadian behavior will be characterized. The power of Drosophila genetics will be used to identify neuronal structures and circadian clock genes required for circadian rhythm synchronization by temperature cycles. Finally, biochemical techniques will be used to elucidate the molecular mechanisms by which the pacemaker responds to temperature inputs. Determining how temperature and other environmental inputs are integrated in a simple model system will provide information on how external inputs can act independently and synergistically to affect the timing of complex behaviors such as sleep. This should ultimately lead to a better understanding and treatment of illnesses linked to circadian rhythms, such as sleep disorders, shift-work associated complications, seasonal affective and bipolar disorder. [unreadable] [unreadable]